Worcester Bosch · Greenstar Highflow CDi ErP
U1 boiler fault code
Greenstar Highflow 440CDi ErP & 550CDi ErP
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What U1 means
Boiler flow temperature is too high; the boiler will shut down until it has cooled down.
Gas Safe engineer: Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.
Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
Safe check
Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
When to contact an engineer
Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
Source and provenance
- Worcester Bosch Greenstar Highflow CDi ErP User Instructions · 6 720 818 076 (2015/12) · §7.1 Error codes, printed p. 14
user instructions
2015/12 · 6 720 818 076